Redesign the way anonymous fields are handled in designated-initializers.

Previously designated anonymous fields were found via name lookup. This redesign uses the fact that an IndirectFieldDecl declaration will always follow an anonymous implicit field to remove the special case of name lookup. 

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@122387 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 31 insertions, 67 deletions

diff --git a/lib/Sema/SemaInit.cpp b/lib/Sema/SemaInit.cpp
index 555166076d..3cca42e48b 100644
--- a/lib/Sema/SemaInit.cpp
+++ b/lib/Sema/SemaInit.cpp
@@ -1194,55 +1194,29 @@ void InitListChecker::CheckStructUnionTypes(const InitializedEntity &Entity,
                           StructuredList, StructuredIndex);
 }
 
-/// \brief Similar to Sema::BuildAnonymousStructUnionMemberPath() but builds a
-/// relative path and has strict checks.
-static void BuildRelativeAnonymousStructUnionMemberPath(FieldDecl *Field,
-                                    llvm::SmallVectorImpl<FieldDecl *> &Path,
-                                    DeclContext *BaseDC) {
-  Path.push_back(Field);
-  for (DeclContext *Ctx = Field->getDeclContext();
-       !Ctx->Equals(BaseDC);
-       Ctx = Ctx->getParent()) {
-    ValueDecl *AnonObject =
-      cast<RecordDecl>(Ctx)->getAnonymousStructOrUnionObject();
-    FieldDecl *AnonField = cast<FieldDecl>(AnonObject);
-    Path.push_back(AnonField);
-  }
-}
-
 /// \brief Expand a field designator that refers to a member of an
 /// anonymous struct or union into a series of field designators that
 /// refers to the field within the appropriate subobject.
 ///
-/// Field/FieldIndex will be updated to point to the (new)
-/// currently-designated field.
 static void ExpandAnonymousFieldDesignator(Sema &SemaRef,
                                            DesignatedInitExpr *DIE,
                                            unsigned DesigIdx,
-                                           FieldDecl *Field,
-                                        RecordDecl::field_iterator &FieldIter,
-                                           unsigned &FieldIndex,
-                                           DeclContext *BaseDC) {
+                                           IndirectFieldDecl *IndirectField) {
   typedef DesignatedInitExpr::Designator Designator;
 
-  // Build the path from the current object to the member of the
-  // anonymous struct/union (backwards).
-  llvm::SmallVector<FieldDecl *, 4> Path;
-  BuildRelativeAnonymousStructUnionMemberPath(Field, Path, BaseDC);
-
   // Build the replacement designators.
   llvm::SmallVector<Designator, 4> Replacements;
-  for (llvm::SmallVector<FieldDecl *, 4>::reverse_iterator
-         FI = Path.rbegin(), FIEnd = Path.rend();
-       FI != FIEnd; ++FI) {
-    if (FI + 1 == FIEnd)
+  for (IndirectFieldDecl::chain_iterator PI = IndirectField->chain_begin(),
+       PE = IndirectField->chain_end(); PI != PE; ++PI) {
+    if (PI + 1 == PE)
       Replacements.push_back(Designator((IdentifierInfo *)0,
                                     DIE->getDesignator(DesigIdx)->getDotLoc(),
                                 DIE->getDesignator(DesigIdx)->getFieldLoc()));
     else
       Replacements.push_back(Designator((IdentifierInfo *)0, SourceLocation(),
                                         SourceLocation()));
-    Replacements.back().setField(*FI);
+    assert(isa<FieldDecl>(*PI));
+    Replacements.back().setField(cast<FieldDecl>(*PI));
   }
 
   // Expand the current designator into the set of replacement
@@ -1250,23 +1224,20 @@ static void ExpandAnonymousFieldDesignator(Sema &SemaRef,
   // member of the anonymous struct/union is actually stored.
   DIE->ExpandDesignator(SemaRef.Context, DesigIdx, &Replacements[0],
                         &Replacements[0] + Replacements.size());
+}
 
-  // Update FieldIter/FieldIndex;
-  RecordDecl *Record = cast<RecordDecl>(Path.back()->getDeclContext());
-  FieldIter = Record->field_begin();
-  FieldIndex = 0;
-  for (RecordDecl::field_iterator FEnd = Record->field_end();
-       FieldIter != FEnd; ++FieldIter) {
-    if (FieldIter->isUnnamedBitfield())
-        continue;
-
-    if (*FieldIter == Path.back())
-      return;
-
-    ++FieldIndex;
+/// \brief Given an implicit anonymous field, search the IndirectField that 
+///  corresponds to FieldName.
+static IndirectFieldDecl *FindIndirectFieldDesignator(FieldDecl *AnonField,
+                                                 IdentifierInfo *FieldName) {
+  assert(AnonField->isAnonymousStructOrUnion());
+  Decl *NextDecl = AnonField->getNextDeclInContext();
+  while (IndirectFieldDecl *IF = dyn_cast<IndirectFieldDecl>(NextDecl)) {
+    if (FieldName && FieldName == IF->getAnonField()->getIdentifier())
+      return IF;
+    NextDecl = NextDecl->getNextDeclInContext();
   }
-
-  assert(false && "Unable to find anonymous struct/union field");
+  return 0;
 }
 
 /// @brief Check the well-formedness of a C99 designated initializer.
@@ -1386,7 +1357,17 @@ InitListChecker::CheckDesignatedInitializer(const InitializedEntity &Entity,
     for (; Field != FieldEnd; ++Field) {
       if (Field->isUnnamedBitfield())
         continue;
-
+      
+      // If we find a field representing an anonymous field, look in the
+      // IndirectFieldDecl that follow for the designated initializer.
+      if (!KnownField && Field->isAnonymousStructOrUnion()) {
+        if (IndirectFieldDecl *IF =
+            FindIndirectFieldDesignator(*Field, FieldName)) {
+          ExpandAnonymousFieldDesignator(SemaRef, DIE, DesigIdx, IF);
+          D = DIE->getDesignator(DesigIdx);
+          break;
+        }
+      }
       if (KnownField && KnownField == *Field)
         break;
       if (FieldName && FieldName == Field->getIdentifier())
@@ -1427,16 +1408,8 @@ InitListChecker::CheckDesignatedInitializer(const InitializedEntity &Entity,
           ++Index;
           return true;
         }
-      } else if (!KnownField) {
-        // Determine whether we found a field at all.
-        ReplacementField = dyn_cast<FieldDecl>(*Lookup.first);
-        
-        // Check if ReplacementField is an anonymous field. 
-        if (!ReplacementField)
-          if (IndirectFieldDecl* IField = dyn_cast<IndirectFieldDecl>(*Lookup.first))
-            ReplacementField = IField->getAnonField();
       }
-
+ 
       if (!ReplacementField) {
         // Name lookup found something, but it wasn't a field.
         SemaRef.Diag(D->getFieldLoc(), diag::err_field_designator_nonfield)
@@ -1447,16 +1420,7 @@ InitListChecker::CheckDesignatedInitializer(const InitializedEntity &Entity,
         return true;
       }
 
-      if (!KnownField && 
-          cast<RecordDecl>((ReplacementField)->getDeclContext())
-                                                 ->isAnonymousStructOrUnion()) {
-        // Handle an field designator that refers to a member of an
-        // anonymous struct or union. This is a C1X feature.
-        ExpandAnonymousFieldDesignator(SemaRef, DIE, DesigIdx,
-                                       ReplacementField,
-                                       Field, FieldIndex, RT->getDecl());
-        D = DIE->getDesignator(DesigIdx);
-      } else if (!KnownField) {
+      if (!KnownField) {
         // The replacement field comes from typo correction; find it
         // in the list of fields.
         FieldIndex = 0;